Fuse unit



3 Sheets-Sheet 1 A. H. POWELL FUSE UNIT Filed June 29, 1944 Oct. 21, 1947.

Oct. 21, 1947.

A. H. POWELL 2,429,2374

FUSE UNIT Filed June 29, 1944 3 Sheets-Shes?l 2 37 Inventor: Alric: THDOWQI l, .7e/M."

His Attorney.

Oct.. 2l, 1947. A, H, PQWELL 2,429,237

FUSE UNIT FiledI June 29, 1944 s sheets-'sheet s 7 by s 8652v 7'/ His Attorney.

Patented ct. 221, 1.947

FUSE UNIT Alric H. Powell, Yeadon, Pa., assignor to General Electric Company, a corporation of New York Application June 29, 1944, Serial No. 542,725

11 Claims. l

My invention relates to fuse units, and more particularly to fuse units employing fuses of the type disclosed and claimed in copending application Serial No. 542,726, Williams et al., filed conf currently with the present application and assigned to the same assignee as the present application.

The fuse units of my invention have many applications but they are particularly adapted for use on aircraft. At the present time the motors and controls on large aircraft have generally been supplied from a direct current source of power. It has recently been proposed to supply the electrical energy for the various motors and controls on large aircraft with ralternating current of a frequency in the neighborhood of 400 cycles. The circuits for supplying this power are arranged'so as to comprise numerous parallel paths each taking a more or less different course. Each of these parallel paths should be protected by a suitable circuit interrupting device. The fuse unit of my invention has been found satisfactory for such use.

It is an object of my invention to provide a new and improved fuse unit.

It is another object of my invention to provide a fuse unit which is simple and inexpensive to manufacture, and accurate and dependable in operation.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to the accompanying drawings in which Fig. 1 is a plan view of a fuse unit embodying my invention; Fig. 2 is a sectional view taken on line 2--2 of Fig. 1 with the fuse device shown in full; Fig.v 3 is a sectional view taken on line 3-3 of Fig. 1 with a portion of the handle of the fuse device cut away; Fig. 4 is a plan View partly in section similar to Fig. 1 of a modication of my invention; Fig. 5 is a sectional view taken on line 5-5 of Fig. 4; Fig. 6 is a sectional View taken on line 6 6 of Fig. 5; Fig. 7 is an end view partly in section of a fuse unit embodying still another modification of my invention; Fig. 8 is a plan View similar to Fig. 1 of still another modification of my invention; Fig. 9 is a sectional view taken on line 9-9 of Fig. 8; Fig. 10 is a sectional view taken on lineIIJ--IU ofFig. 9 with certain parts broken away, and Fig. 11 is a sectional view similar to Fig. '10 with certain parts broken away and with the fuse locking device out of its locking position.

Referring now to Figs. 1, 2 and 3 of my invention, there is disclosed a fuse device I of the type disclosed and claimed in the above mentioned Williams et al. application. This fuse device comprises a pair of molded ferrules 2 and 3 of insulating material into which a plurality of blade-like conductors 4 are molded in spaced parallel relation. Each of the blade-like conductors 4 is provided with a notched-out portion 5. A plurality of fusible elements indicated at 6 in Fig. 2 interconnect thek corresponding conductors 4 associated with ferrules 2 and 3. These fusible elements extend through holes drilled longitudinally through conductors 4 and are fastened thereto by solder or the like as indicated at l. Each fusible element is enclosed by a fuse tube Il and the ends of the fuse tubes are adapted to fit into recesses 9 in insulating ferrules 2 and 3. Suitable fastening means such as screws I 0 firmly hold the plurality of fuse tubes 8, ferrules 2 and 3 and associated conductors 4 as a unitary assembly. As is described in the above mentioned Williams et al. application, the fuse tubes 8 are filled with a granular, inert, arc quenching material which may be inserted into the fuse tubes after assembly of the fuse device through openings II in ferrule 3, which openings may be closed by a suitable filler plug I2 of cement or the like after the filling operation.

The ferrule 2 is provided with an integral extension I3 which serves as a handle to manually grasp the fuse device I for removing and inserting it with respect to an associated electrical circuit. In addition, the ferrule 2 of fuse device I also includes an integral extension I4 which is adapted to be engaged by cooperating locking means to be described hereinafter.

The fuse device I is adapted to cooperate with a base I5 to form the fuse unit of my invention. Supported from and suitably secured to each end of base I5 is an insulating member I6 having a plurality of barriers II between which are defined a plurality of recesses I8. Mounted in each recess I8 is a spring terminal clip IIS having an extension 20. A terminal screw 2l passing through an opening in the extension 2U holds each spring terminal clip I9 in position in recess I8 in insulating member I6.

In order that vibration will not cause the fuse device I to move out of contact with terminal clips I9, I provide an insulating pin 22 which passes through a plurality of the barriers I'I at one end of the base I5 so as to engage at least two blade contacts 4, as is clearly shown in Fig. 1, whereby the corresponding end of fuse device I is securely held in position. In order to hold the other end of fuse device I in engagement with spring terminal clips I9 pivotally mounted latching member 23 is provided having integrally formed trunnions 24 adapted to be mounted in a recess in insulating member I6. A suitable spring is provided with one end engaging with a notch 29 in pivotally mounted latching member 23, while the other end engages with a recess 21 in insulating member I5. Spring 25 biases latching member 23 in a counter-clockwise direction as viewed in Fig. 3 so as to engage integral extension I4 of insulating ferrule 2.

To remove the fuse device I it is merely necessary to grasp the knurled portion 28 of latching member 23 with the thumb of one hand rotating it in a clockwise direction to the dotted position shown in Fig. 3. The handle I3 of the fuse device I may then be grasped with the other hand to remove the fuse device which must be moved upwardly at the end comprising the ferrule 2 so that the other end may be moved from beneath insulating pin 22.

Referring now to Figs. 4, 5 and 6, I have illustrated a modification of my invention insofar as the locking means for holding the fuse in position is concerned. The corresponding parts in Figs. 4, 5 and 6 are designated by the same reference numerals as in the preceding figures. The ferrule of insulating material for the fuse device which has been designated as I to distinguish it from the fuse device I of Fig 1 diiers from the ferrule 2 of Fig. 1 and is designated by the numeral 39. Ferrule 30 includes a handle portion 3i. Reciprocatingly mounted in a recess 32 in handle SI is a manually engageable plunger 33 which is normally biased by a spring means 34 mounted within recess 32 to assume the position indicated in Fig. 6. The manually engageable plunger 33 has a portion thereof cut away to form a cam surface 35. An inverted L-shaped member suitably fastened to screw IG as by means of a nut 3l has a portion thereof substantially perpendicular with plunger 33, with the end thereof cut off at an angle, as indicated at 38 to engage with the cam surface 35, as is clearly shown in Fig. 4. A spring member 39 also fastened to screw Iii by means of nut 31 biases inverted L- shaped member 38 into engagement with cam surface 35. It is obvious that when plunger 33 is pushed into recess 32 against the force of spring 34, that cam 35 forces inverted L-shaped member 3B to move away from the handle 3|. Extending through an opening in L-shaped member 39 is a latching pin 49 which also extends through an opening 4I in handle 3I. Spring 39 normally biases pin 49 in a direction so as to move toward the right, as viewed in Fig. 5. The end of pin 4I engages with a catch 42 which may be molded as an integral part of one of the barriers II of the insulating member designated as Iii in Fig. 4 to distinguish it from members I5 in Fig. 2. The particular barrier having integrally formed therewith the latch 42 has been designated as Il. The insulating members I5 are secured to the base I5 by suitable means such as screws I5', one of which appears in Fig. 5,

From the above discussion it will be obvious that fuse device I' may be removed from engagement with spring terminal clips I9 merely by grasping the handle 3I and at the same time depressing plunger 33 whereby inverted L-shaped member 35 assumes the dotted position shown in Fig. 5 with the consequent withdrawal of pin 40 from engagement with catch 42. After the latching means is released the fuse device is removed in exactly the same manner as was discussed in connection with Figs, 1 to 3.

In Fig. 7 I have illustrated still another modification of my invention disclosed in Figs. 4, 5 and 6. The handle of the fuse device has been designated by the numeral 43. The manually depressible plunger 44, similar to the plunger 33 of Fig. 4, is reciprocably mounted in recess 45 in handle 43. A latching pin 46, similar to the latching pin 40 of Fig. 4, is provided. This latching pin, however, is arranged parallel with the plunger 44 as contrasted with the arrangement disclosed in Figs. 4, 5 and 6, where the latching plunger is arranged at right angles to the manually depressible plunger. Latching plunger 46 is reciprocably mounted in a recess -4'I in handle 43 and is biased in an outward direction by spring means 43 so as to engage a catch 49 formed as a part of the insulating member I6 which is very similar to insulating members I5 and I6 described above. The handle 43 is provided with a recess 50 into which catch 49 may move to be engaged by latching pin 4E. Manually engageable plunger 44 and latching pin 45 are interconnected by a lever 5| pivotally mounted as indicated at 52 substantially at the midpoint thereof. When manually engageable plunger 44 is depressed into recess 45, lever 5I will rotate in a clockwise direction, as viewed in Fig. 'l and withdraw latching pin or plunger 46 out of engagement with catch 49 whereupon the fuse device may be removed out of engagement with spring terminal clips I9 in the same manner as in Figs. 1 and 4.

Fuse units embodying my invention may be used to protect a plurality of parallel circuits. Insuch a case it is important not only that the contact resistance at the terminals of the fuse device is low, but furthermore that the contact resistances of the parallel arranged fuse terminals are substantially equal. Otherwise the fuse device will not carry equal currents in all of its parallel paths with the possible progressive failure of the fusible elements in a multi-path fuse device. This is particularly important in connection with fuse units carrying higher currents and in Figs. 8, 9, 10 and 1l I have disclosed another embodiment of my invention including the anti- Vibration locking arrangement described above combined with means for insuring very low contact resistance at each of the terminals of the multipath fuse device.

Referring now to Figs. 8 to l1, inclusive, there is disclosed a fuse unit generally indicated at 53 which is substantially identical with the fuse unit disclosed and claimed in the copending Williams et al. application referred to above. This fuse unit comprises a pair of molded ferrules 54 and 55 of insulating material into which a plurality of blade-like conductors 5,6 are molded in spaced parallel relationship. Each of the blade-like conductors 56 is provided with a notched-out portion 5l. A plurality of fusible elements 59 and 59 shown in Figs. l0 and 1l interconnect each pair of corresponding conductors 56. These fusible elements extend through holes drilled longitudinally through conductors '56 and are fastened thereto by solder indicated at 5D. Each pair of fusible elements interconnecting respective conductors 56 associated with ferrules 54 and 55 is enclosed by a fuse tube 6I and the ends of fuse tubes are adapted to fit in recesses B2 molded in insulating ferrules 54 and 55 on the sides cpposite from which conductors 56 extend. Suitable fastening means are provided to firmly hold the plurality of fuse tubes llil, ferrules 54 and 55 and the associated blade-like conductors 56 as aunitary assembly. As is described in the above mentioned Williams et al. application, the fuse tubes 6| are lled with a granular, inert,arc quenching material which may be inserted into the fuse tubes after assembly of the fuse device through openings 63 in ferrule 55, which openings may be closed by a suitable filler plug `84 of cement or the like after the lling operation.

The fuse device 55 of Figs. 8 to 1l is adapted to cooperate with a base 65 having supported from either end thereof insulating members 66 and 61, respectively, which, as shown in Fig, 9, are secured to the base by suitable means such as screws 65 indicated in dotted lines. These insulating members are provided with a plurality of barriers 68 between which are dened a plurality of recesses 69. Mounted in each recess 69 is a spring terminal clip 16, best shown in Figs. l0 and l1. These spring terminal clips are suitably fastened by means of screws 1I within each recess 89. Each spring terminal clip 1S is provided with an extension 12 and a terminal screw 13 passes through an opening in extension 13 to aid in holding the spring terminal clip in position in recess 69 and also to provide means whereby electrical connection with an associated circuit may readily be made.

In order that vibration will not cause the fuse device 53 to move out of engagement with spring terminal clips 10, I provide a locking bar 14 of insulating material which is pivotallyy mounted at 15 to insulating member 61. The free end of locking bar 14 is provided with an upwardly eX- tending handle 16 which may be grasped manually to move locking bar 14 about pivot 15. Locking bar 14 is also provided with an integral extension 11 which is adapted to be engaged by a pivotally mounted latching member 18 which may be substantially identical to the latching member 23 of Figs. 1 to 3. Latching member 18 having integrally formed trunnions 19 is pivotally mounted in a recess in insulating member 66 and is biased by means of a spring 88 into latching engagement with extension 11.

In order to insure that the contact resistance between contact blades 56 and spring terminal clips is very low thereby insuring uniform distribution of current between the paths of the multi-path fuse device 53 when used to protect a plurality of parallel circuits. I provide a plurality of compression springs 8|. These springs 8l are arranged so that one end of a spring engages With one'sicle of a spring terminal clip 10. The springs 8| engaging the outside terminal clips 10 of the fuse unit have the other ends thereof engaging the outside barriers 58. The intermediate springs 8| have the ends thereof which are not in engagement with contact clips 18 in engagement with an insulating spring supporting member 82. Insulating spring supporting members 82 have the upper portions thereof diverging as is clearly shown in Figs. 10 and 11, the purpose c-f which will become apparent hereinafter. Each insulating spring supporting member 82, as best shown in Fig. 9, has a necked-down portion 83 so that pairs of members 82 may be held in slidable arrangement in retaining members 84. Each insulating member 82, as is best shown in Fig. 11, is provided with a protrusion 85 for supporting one end of coiled compression spring 8|. The

other 'end of the coiled compression spring is supported ona corresponding protrusion 86 formed integrally with the terminal clip 10. Spring terminal clips 10 and compression springs 8| are arranged so that the fuse device 53 may be readily inserted and removed `without too much binding action von blade contacts 56. The position of these contacts when the locking bar 14 is out of its locking position is clearly indicated in Fig. 11.

In order to reduce the contact resistance to substantially zero, locking bar 14 is provided with a plurality of extensions 81 and 88. The extensions 88 are adapted to move between the diverging portions of insulating spring supporting members 82 associated with insulating member 66 when the locking bar 14 is moved into its locking position indicated in Fig. 10, whereupon the springs 8i are compressed to insure high contact pressure. The extensions 81 move between the diverging portions of insulating spring supporting members 82 mounted inthe recesses 69 in insulating member 61. The extensions 81 and 88 are tapered at the free ends thereof in order to facilitate insertion between insulating spring supporting members 82.

To remove fuse device 53 it is merely necessary to move latching member 18 out of engagement with extension 11 whereupon locking bar 14 may be rotated to the dotted position indicated in Fig. 9. Such rotation of locking bar 14 removes members 81 and 88 from between insulating spring retainers 82 (see Fig. 11) whereby the contact pressure on blade contacts 56 is greatly reduced. The fuse device53 may then readily be removed.

It will be apparent to those skilled in the art that my invention is not limited to the particular construction shown by that changes and modications may be made without departing from the spirit and scope of my invention, and I aim in the appended claims to cover all such changes and modifications.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1 In a fuse unit, a base, a plurality of stationary contacts mounted on said base, a fuse device havinga plurality of contacts for engaging said stationary contacts when said fuse device is in its current carrying position, a pair of insulating ferrules associated With said fuse device, one of said ferrules having an integral extension, and a pivotally mounted latch on said base for engaging said integral extension to prevent vibration from moving said fuse device out of position.

2. In a fuse unit, a base, a plurality of stationary contacts mounted on said base, a fuse device having a plurality of contacts for engaging said stationary contacts When said fuse device is in its current carrying position, a pair of insulating ferrules associated with said fuse device, one of said ferrules having an integra] extension of insulating material, a pivotally mounted latch on said base, and spring means for biasing said latch into engagement with said integral extension to prevent vibration from moving said fuse device out of position.

3. In a. fuse unit, a base, a plurality of stationary contacts mounted on said base, a fuse device having a plurality of contacts for engaging said stationary contacts when said fuse device is in its current carrying position, a pair of insulating ferrules associated with said fuse device, one of said ferrules having an extension of insulating material serving as a handle so that said fuse device may be withdrawn manually from l! l said stationary contacts, means for latching said fuse device into position against the eiects of vibration, and manually engageable means for releasing said latching means to permit removal of said fuse device.

4. In a fuse unit, a base, a plurality of stationary contacts mounted on said base, a fuse device having a plurality of contacts for engaging said stationary contacts when said fuse device is in its current carrying position, a pair of insulating ferrules associated with said fuse device, means ior latching said fuse device into position against the eiects of vibration, and means for releasing said latching means.

5. In a fuse unit, a base, a plurality of stationary contacts mounted on said base, a fuse device having a plurality of contacts for engaging said' stationary contacts when said fuse device is in its current carrying position, a pair of insulating ferrules associated with said fuse device, one of said ferrules having an integral extension of insulating material serving as a handle so that said fuse device may be withdrawn manually from said stationary contacts, means associated With one end of said base for holding one end o said fuse device in position against vibration or .the like, and a releasable latching means for removably holding the other end of said fuse device in position.

6. In a fuse unit, a base, a plurality of stationary contact clips mounted on said base, spring means for applying contact pressure to said clips, a fuse device having contacts for engagement with said contact clips, and a member pivotally mounted on said base for holding said fuse device in position against vibration and for compressing said spring means to increase the contact pressure between said contact clips and said contacts oi said fuse device.

7. In a fuse unit, a base, a plurality of stationary contact clips mounted on said base, spring means for applying contact pressure to said clips, a fuse device having blade type contacts for engagement with said contact clips, and a member pivotally mounted .on said base for compressing said spring means to increase the contact pressure between said contact clips and blade type contacts.

8. In a fuse unit, a base, a plurality of stationary contacts mounted on said base,- a fuse device having contacts for engagement Withsaid stationary contacts, a member pivotally mounted on said base for holding said fuse device in current .carrying position with said stationary contacts, and latching means for removably latching said member to prevent vibration from effecting said fuse device.

9. In a fuse unit, a base, a plurality of stationary contact clips mounted on said base, compression spring means for applying contact pressure to said clips, a fuse device having blade type contacts for engagement with said contact clips, a member pivotally mounted on said base for holding said fuse device in position against vibration and shock, and a plurality of extensions on said member for compressing said spring means to increase the contact pressure between said contact clips and blade type contacts.

10. In a `fuse unit, a base, a plurality of stationary contacts mounted .on said base, a fuse device having a plurality of contacts for engaging said stationary contacts when said fuse device is in its current carrying position, a pair of insulating ierrules associated with said fuse device, one of said ferrules having an extension of insulating material serving as a handle so that said fuse device may be withdrawn manually from said stationary contacts, means for latching said fuse device into position against the effects of vibration, and means comprising a plunger reciprocally mounted in said extension for releasing said latching means to permit removal of said fuse device.

11. In a fuse unit, a base, a plurality of stationary contacts mounted on said base, a fuse device having a plurality of contacts for engag ing said stationary contacts When said fuse device is in its current carrying position, a pair of insulating ferrules associated with said fuse device, one of said ferrules having an extension of insulating material serving as a handle so that said fuse device may be Withdrawn manually from said stationary contacts, means for latching said fuse device into position against the effects of vibration, means comprising a plunger reciprocally mounted in said extension, and a cam associated with said plunger for releasing said latching means to permit removal of said fuse device upon actuation of said plunger.

ALRIC H. POWELL.

REFERENCES CITED The following references are oi record in the file or this patent:

UNITED STATES PATENTS Number Name Date 897,525 De Reamer Sept. 1, 1908 991,005 Murray May 2, 1911 FOREIGN PATENTS Number Country Date V'7,568 Great Britain Apr. 1, 1903 

